WFS-T xmlhttp post length limits?

After a long time searching and trying I'm asking now for help:

My situation:

I've a jquery/openlayers-app which allows the user to create simple geoemtries with attributes over WFS-T...
I'm running on debian6 with tomcat6(:80-iptables) and geoserver 2.1.3(jetty:8181). All cross domain issues between tomcat and geoserver are solved with a simple jsp-proxy
The users can view all my wfs-layers without any problem and are able do create simple geometries

My problem:

Users creating more complex geometries are not able to save it over wfs-t. More complex means that the resulting XML-POST content length exceeds approx. 2100 characters. POST's with e.g. 2000 characters are inserted successfully.
I've digged into the tomcat-server settings and disabled all limits (maxHTTPHeaderSize,maxSavePostSize,...) and also elevated the maxpostsize in the geoserver-jetty webserver --> NO EFFECT
Following the response error message when a user creates more complex geometries:

org.xml.sax.SAXParseException: An invalid XML character (Unicode: 0x0) was found in the element content of the document. An invalid XML character (Unicode: 0x0) was found in the element content of the document.

I've no idea why my XML POST request is causing an Unicode-error everytime i add one more vertex to a geometry which i successfully inserted before.
my request and response code:

successful POST request

successful response

successful POST request headers

not successful POST request

not successful response

not successful POST request headers

my jsp-proxy

I'm very happy for any hint how to solve my problem!

Thanks in advance,

Cheers Hubert

Solution

Better late than never :) Code below works for large geometries (at least for me)

Oh YEAH this is code for simple jsp proxy

<%@page session="false"%>
<%@page import="java.net.*,java.io.*" %>
<%@page trimDirectiveWhitespaces="true"%> 
<%

/**
 * This is a white list proxy that could be used the prevent an error due to 
 * JavaScript Same Origin Policy.
 * 
 * CAUTION: It might break some sites and it's a security risk because
 * people can use this proxy to browse the web and possibly do bad and/or illegal stuff
 * with it. 
 * It can load any content type.
 * This proxy implementation was inspired by the proxy.cgi script of OpenLayers
 * {@link http://openlayers.org}
 * To use this in OpenLayers you have to set OpenLayers.ProxyHost = "Url/To/This/Proxyfile/proxy.jsp?";
 * within your JavaScript code <br>
 * The base code of the proxy has been provided by SNIPPLR
 * {@link http://snipplr.com/view/17987/jsp-proxy-for-javascript-applications/}
 * 
 * @author terrestris GmbH & Co. KG
 * @author Christian Mayer
 * @author Marc Jansen
 * 
 * @license BSD see license.txt
 * 
 */
String[] allowedHosts = {
    "www.openlayers.org", "openlayers.org", 
    "labs.metacarta.com", "world.freemap.in", 
    "prototype.openmnnd.org", "geo.openplans.org",
    "sigma.openplans.org", "demo.opengeo.org",
    "www.openstreetmap.org", "sample.azavea.com",
    "v-swe.uni-muenster.de:8080", 
    "vmap0.tiles.osgeo.org",
    "192.168.197.95:8080"
};
HttpURLConnection con = null;
try {
    String reqUrl = request.getQueryString();
    String decodedUrl = "";
    if (reqUrl != null) {
        reqUrl = URLDecoder.decode(reqUrl, "UTF-8");
    }
    else {
        response.setStatus(400);
        out.println("ERROR 400: No target specified for proxy.");
    }

    // extract the host
    String host = "";
    host = reqUrl.split("\\/")[2];
    boolean allowed = false;

    // check if host (with port) is in white list
    for (String surl : allowedHosts) {
        if (host.equalsIgnoreCase(surl)) {
            allowed = true;
            break;
        }
    }

    // do the proxy action (load requested ressource and transport it to client)
    // if host is in white list
    if(allowed) {
        // replace the white spaces with plus in URL
        reqUrl = reqUrl.replaceAll(" ", "+"); 

        // call the requested ressource     
        URL url = new URL(reqUrl);
        con = (HttpURLConnection)url.openConnection();
        con.setDoOutput(true);
        con.setRequestMethod(request.getMethod());
        String reqContenType = request.getContentType();
        if(reqContenType != null) {
            con.setRequestProperty("Content-Type", reqContenType);
        }
        else {
            con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
        }

        int clength = request.getContentLength();
        if(clength > 0) {
            /* NOT WORKING FOR LARGE POST BODY
            con.setDoInput(true);
            byte[] idata = new byte[clength];
            request.getInputStream().read(idata, 0, clength);
            con.getOutputStream().write(idata, 0, clength); 
            */
            con.setDoInput(true);
            InputStream istream = request.getInputStream();
            OutputStream os = con.getOutputStream();
            final int length = 5000;
            byte[] bytes = new byte[length];
            int bytesRead = 0;
            while ((bytesRead = istream.read(bytes, 0, length)) > 0) {
                os.write(bytes, 0, bytesRead);
            }
        }

        // respond to client
        response.setContentType(con.getContentType());

        BufferedReader rd = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String line;
        int i = 0;
        while ((line = rd.readLine()) != null) {
            out.println(line);  
        }
        rd.close();
    }
    else {
        // deny access via HTTP status code 502
        response.setStatus(502);
        out.println("ERROR 502: This proxy does not allow you to access that location.");
    }

} catch(Exception e) {

    // resond an internal server error with the stacktrace
    // on exception
    response.setStatus(500);
    byte[] idata = new byte[5000];

    if(con.getErrorStream() != null) {
        con.getErrorStream().read(idata, 0, 5000);
    }

    out.println("ERROR 500: An internal server error occured. " + e.getMessage() + " " + new String(idata));    
}
%>